Hydraulic surface grinding machine



Oct. 31, 1944.

H. A. SILVEN 2,361,903

HYDRAULIC SURFACE GRINDING MACHINE Filed Jan. 23, 1942 HERBERT A. 5ll .VEN

Patented Oct. 31, 1944 1 HYDRAULIC SURFACE. GRINDING MACHINE Herbert A. Silven, Worcester, Mass, assignor to Norton Company, Worcester, Mass, a corporatlon of Massachusetts Application 3 Claims.

The invention relates to grinding machines, and more particularly to a hydraulically operated surface grinding machine for grinding plane surfaces on a'work piece.

One object of the invention isto provide a simple and thoroughly improved hydraulically operated surface grinding machine. Another object of the invention is to provide an improved hydraulically operated surface grinding machine in which the work table is reciprocated longitudinally by an hydraulically operated mechanism and the wheel slide is indexed or traversed transversely by an hydraulically operated mechanism which is controlledby and in timed relation with the table reciprocating movement.

A furtherobject of the invention is to provid a hydraulically operated table reciprocating mechanism which. may be stopped precisely in a predetermined position. A further object of the invention is to provide a hydraulically operated table traversing mechanism in which means are provided to supply fluid to the fluid pressure delivery pipe line after the pressure fluid from the iluid pump is cut off to prevent creeping of the table in the reverse direction.

Another object of the invention is to provide a hydraulically operated table' reciprocating mechanism with a connection including a check valve between the reservoir and the fluid pressure delivery pipe line to prevent the creation of a' vacuum within the table cylinder so that the table may be stopped in 'a predetermined position for a grinding wheel truing operation. Other objects will be in part obviousor in part pointed out hereinafter.

The invention accordingly consists-in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and.

the scope of the application of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of various possible embodiments of the January 23, 1942, Serial No. 427,955

the grinding wheel 12.

ried b an upwardly extending portion of the base In.

The grinding wheel feeding mechanism is preferably of a type similar to the well known feeding mechanism such as shown in the prior U. S. Patent 'to Norton, No. 1,108,779 dated August 25, 1914, and the U. S. Patent to H. A. Silven, No. 2,269,697 dated January 13, 1942.

A hydraulically operated mechanism is, provided for reciprocating the table I i to reciprocate the work piece I6 beneath the operative face of In the preferred form the reciprocating mechanism may comprise a cylinder 2! which is fixedly mounted within the base Not the machine. A piston 22 is slidably mounted within the cylinder 2| and is connected to one end of a piston rod 23. The other end of the piston rod 23 is connected to a bracket 24 depending from the under side of the table II. The base 10 is provided with a reservoir 25 from which fluid may be pumped through a pipe 26 by means of a motor driven fluid pump 21. The pump 21 forces fluid under pressure through a pipe 28 to amain control valve 30. A pressure relief valve 3| is provided in the pipe line 28 whereby excess fluid under pressure may be passed directly through a pipe 32 into the reservoir 25.

. on the outer end of the valve stem 33.

. The main control valve 30 is a piston type valve l comprising a valve stem 33 having formed integrally therewith valve pistons 34, 35 and 36. The main control lever 31 is pivotally supported by a stud 38 which is carried by a bracket 39. The

bracket 39 is fixedly supported on the front of the machine base. The lever 31 is connected by a pair of diametrically opposed, spaced. aligned pins 40 with a spool-shaped member 4| mounted It will be readily apparent from the foregoing disclosure that movement of the control lever-3l serves to shift the valve stem 33 to change the position of the valve pistons as desired. In the position of the valve 30 shown in the figure, fluid under pressure passing through the pipe 28 enters a valve chamber 42 located between the valve pistons 34 and 35 and passes outthrough a pipe 43 to the reservoir 25. v

, When it is clesiredto start the reciprocatory movement of the table I I, the main control lever "ated either manually or by power.

and the table II in a longitudinal direction. In

the position of the valve 48 shown in the figure, fluid under pressure passes through the pipe 52 into the cylinder chamber 54 to move the piston 22, the piston rod 23, and the table II toward the right. During this movement, fluid within the cylinder chamber 55 exhausts through the passage 53, the port 58, and through an exhaust passage 56 in the valve member 48 and passes out through a passage 5'! and a pipe 58 to the reservoir 25.

The reversing valve member 48 may be actu- As illustrated in the drawing, a manually operable reversing lever 80 is pivotally mounted on a stud 6| which is fixedly mounted relative to the base I 8. A depending portion of the reversing lever 68 is provided with a gear segment 82 which meshes with a gear segment 83. The gear segment 63 is mounted on the outer end of a rock shaft 84. The inner end of the rock shaft 64 supports a gear segment 65 which in turn meshes with a gear (not shown) mounted on the end of the valve stem (not shown) which is formed integral with the reversing valve member 48.

It will be readily apparent from the foregoing disclosure that when the reversing lever 68 is rocked, motion will be transmitted through the mechanism above described to actuate the reversing valve member 48. In order that the reversing valve may be automatically and rapidly shifted into a reverse position after the reversing lever 68 has moved to a central position, a load and fire mechanism is provided. The gear segment 85 is provided with a downwardly extending arm 18 which serves as a support for a stud. The stud rides in an elongated slot 12 formed in the upper end of a rock arm 13. The rock arm 13 is pivotally supported on a stud 14. A tension spring 15 is connected at its lower end to a stud I6 carried bythe rock arm 13 and its upper end is fastened to a stud which is fixed relative to the base of the machine. This mechanism is substantially identical with that shown in the prior U. S. Patent to Carl G. Flygare and Wallace H. Wood, No. 2,022,542 dated November 26, 1935, to which reference may be had for disclosures not contained herein. It will be readily apparent from the foregoing disclosure that when the reversing lever 88 is shifted, it will transmit a corresponding movement in the reverse direction to the rock arm I3 which increases the tension on the spring 15. After the stud 18 passes by a central position, the released tension of the spring 15 rapidly shifts the lever 68 and gear mechanism above described to shift the reversing valve member 48 into a reverse position to reverse the flow of fluid under pressure to the chambers of the cylinder 2|.

The reversing lever 68 may be actuated manually or may be actuated in timed relation with the reciprocatory movement of the table II by a pair of reversing dogs 11 and 18 which are adjustably supported in a T-slot 18 formed in the front edge of the work table II. The length of the reclprocatory stroke of the table II may be read llly adjusted by shifting the table dogs l1 and 8.

In truing the grinding wheel l2, a truing tool and holder are mounted upon the work table II and the table is thenmoved longitudinally to position the truing tool directly under the grinding wheel, in which position the table is stopped for a truing operation. In using a hydraulically driven table reciprocating mechanism such as that shown in the present case, there is a tendency for the table II to creep in the opposite direction when it has been stopped, thus preventing precise location of the truing tool relative to the grinding wheel. In order to prevent a creeping movement of the table II in the opposite direction when it is stopped, a pipe line is connected with the fluid pressure delivery pipe line 45 at a point adjacent to the table reversing valve 46. A check valve 8| is mounted at the lower end of the pipe I68 and has a short pipe 82 extending into the lower part of the reservoir 25.

Assuming the table II to be traveling in a direction toward the right, that is, with the main control lever 31 shifted in a counterclockwise direction, fluid under pressure from the pump 21 and pipe 28 passes through the pressure delivery line 45 to the table reversing valve 46 and through the central chamber 41 of the rotatable reversing valve member 48 and passes out through the pipe 52 into cylinder chamber 54 to move the piston 22 and table II toward the right.

When it is desired to stop or to reverse the direction of table movement, the main control lever 31 is shifted in a clockwise direction into the position shown in the figure, which movement shifts the valve stem 33 so as to cut of! the passage of fluid under pressure through the fluid pressure delivery pipe 45, as above described. Due to the inertia of the rapidly moving table II,- the table I I together with the piston 22 tends to continue its movement toward the right after the fluid under pressure is cut 08. thus tending to create a vacuum in the cylinder chamber 54. As the piston 22 continues its movement toward the right, a suction effect is obtained which draws fluid directly from the reservoir 25 through the check valve 8|, into the pressure delivery pipe line 45 and valve 46 into the chamber 54, thus maintaining the chamber 54 filled with fluid so that there is no vacuum created which will cause a creeping of the table II in the reverse direction thereto.

The operation of this machine will be readily apparent from the foregoing disclosure. The table II is reciprocated in the manner above described. Assuming the various valves to be adjusted into the positions illustrated, the table II is stationary. When it is desired to start the table movement, the main control lever 31 is moved in a counterclockwise direction to shift the valve stem 33 so that fluid under pressure from the fluid pump 21 and the pipe 28 may pass through the main control valve 30 and out through the fluid pressure delivery line 45 to the table reversing valve 46. This fluid under pressure will pass through the valve 46, the pipe 52, into the cylinder chamber 54 to cause the piston 22 and table II to move toward the right. This movement will continue until the table dog ll engages the reversing lever 68 and shifts the table reversing valve 48 into its reverse position to change the direction of flow of fluid under pressure so that it will enter through the passage so into the cylinder chamber 55 to move the piston 22 and the table II toward the left.

When it is desired to true the, grinding wheel I2, a truing tool (not shown) may be positioned on the table II and the table traversed to locate the diamond directly below the grinding wheel 12, that is, with the cutting point of the diamond in a vertical plane passing through it and the axis of the grinding wheel. When the table II reaches approximately this position, the main control lever 31 is thrown in a clockwise direction into the position shown in the flgure to cut off the flow of fluid under pressure through the delivery pipe 45, thus stopping the table movement and thus tending to create a vacuum in the chamber where the pressure has just been cut ofi, at which point a suction is created withinthe pipe 80 to draw fluid from the reservoir 25, through the pipe 82 and check' valve 8|, into the cylinder chambers 54 or 55, depending upon the directionof reciprocatory movement of the table II. Thus no actual vacuum is created and there is no tendency of the table to creep in a direction toward the left if the table reciprocation is to the right as shown in the figure, thus facilitating stopping the table in a precise and predetermined position for a truing operation.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and a reservoir, means including a fluid pressure pump to convey fluid under pressure from said reservoir to said cylinder, a reversing valve located between the pump and cylinder to control the 4 admission to and exhaust of fluid from said cylcheck valve which is connected;behave P reservoir and the reversing valveto' admi fluid inder, a start and stop valve to'start and stop said table reciprocation, and means including a check valve which is connected between the reservoir and the reversing valve to admit fluid directly from the reservoir to the pressure port of the reversing valve to prevent creeping of the table in the reverse direction when the stop and inder, a start and stop valve located between-the, pump and the reversing valve-to start andijs'topjf' the table reciprocation, and meansincludin directly from the reservoir to the pressure port of the reversing valve to prevent creeping of the table in the reverse direction when the stop and start valve is closed to stop the movement of the table.

3. In a grinding machinehaving a longitudinally reciprocable table, means including a piston and cylinder to reciprocate said table, a fluid pressure system including a motor driven pump, a reversing valve to control the admission to and exhaust of fluid from said cylinder, 9, fluid pressure delivery pipe line connecting said pump and said reversing valve, a manually operable start and stop valve located between the pump and the reversing valve to facilitate starting and stopping the reciprocatory movement of the table, and means including a normally closed check valve connected between the reservoir and the fluid delivery line adjacent to said reversing valve which is arranged to open and draw fluid .directly from the reservoir to prevent a creeping movement of the table in the reverse direction when the stop and start valve is shifted to stop 

